The correction of chronic mitral insufficiency by conventional mitral valve replacement carries a higher postoperative morbidity and mortality than operation for most other valvular lesions. Clinical studies have shown that valvuloplasty performed to correct mitral insufficiency is associated with a lower morbidity and mortality than with valve replacement. It is suggested that the maintenance of the mitral apparatus (chordae tendinae) prevents enlargement of end-diastolic and end-systolic dimensions. By utilizing each ventricle as its own control, the effect of chordal severence after valve replacement on regional and global geometry was examined. Two groups of animals (chronic and acute) were compared.